Physico-chemical characterization of chemotactic activities in non-mastitic and mastitic mammary gland secretions

Date of Completion

January 1998

Keywords

Biology, Animal Physiology|Health Sciences, Pathology|Health Sciences, Immunology

Degree

Ph.D.

Abstract

Migration of immune cells during inflammatory (mastitis) and non-inflammatory (lactation) events occurs by a highly regulated process called chemotaxis. The soluble mediators that regulate chemotactic events are called chemoattractants. This study determined qualitative differences between the chemotactic activity of mastitic mammary secretions, normal lactation stage mammary secretions, and late/dry lactation stage mammary secretions. Also, an in vitro mammary epithelial and myoepithelial cell culture system was used to assess the ability of either of those mammary cells to produce chemoattractants. ^ Mastitic and non-mastitic (normal and dry) mammary secretions all induced neutrophil migration. The chemokine IL-8 was found to be present in mastitic, but not in non-mastitic secretions. Comparison of the physico-chemical characteristics of normal and dry stage secretions showed that the chemotactic activity of normal secretions was sensitive to heat, extreme pH, trypsin, and urea treatments. In contrast, the chemotactic activity of dry secretions was stable at extreme pH, resistant to urea, and sensitive to trypsin. Molecular mass fractionations indicated that the chemotactic activity of normal secretions was present in the <30KDa, whereas in dry secretions the activity was in both the <30Kda and >30KDa fractions. Also, mammary epithelial cell, but not myoepithelial cell cultures were able to be induced to produce chemotactic activity. This activity was found to be IL-8 and was inducible by IL-1 and heat killed S. aureus with α-toxin. ^

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